Astrophotographerhttp://www.maclife.com/taxonomy/term/924/all
enUsing Macs to Take Pictures of Galaxies Far, Far Away...http://www.maclife.com/article/feature/using_macs_take_pictures_galaxies_far_far_away
<!--paging_filter--><p><img alt="image of David illig" class="graphic-left" height="187" src="/files/u36/ODD_2_150.jpg" width="150" /><strong>Case Study:</strong> David Illig<br /><strong>Occupation:</strong> Deep-sky astrophotographer<br /><strong>Gear: </strong> 15-inch and 17-inch MacBook Pros; Santa Barbara Instrument Group STL-1100M astronomical CCD imaging camera; two telescopes; Adobe CS3 and planetarium apps, including Microprojects Equinox, Starry Night Pro, and Software Bisque TheSkyX</p><p>&nbsp;</p><p>Don’t call David Illig a “star gazer.” It’s not that he’s hung up on labels, but he likes to be accurate.</p><p>When asked if his interest in astrophotography started out with a penchant for “star gazing,” he’s too polite to directly contradict our phrasing. “Yes, I began as a visual observer,” he says. “I bought my first telescope in 1982.” And Illig still uses that same Questar telescope, though he’s moved from visual observation to deep-sky photography, which he would gladly spend all his time pursuing, if not for the often-obscured skies above his Maryland home.</p><p><img alt="Illig's observatory" height="313" src="/files/u36/ODD_3_380.jpg" width="380" /><br /><strong>Illig’s observatory from the outside. It’s called Upton Farm Observatory, in honor of his wife Leona’s family farm. It also happens to have the acronym UFO.</strong></p><p>Illig is a bona fide Mac-head who has no fewer than two MacBook Pros and a couple of tower Macs, all of which play roles in his cosmological obsession. He hesitates to reveal—for security reasons—exactly how much he’s spent on his observatory equipment, but his setup includes two telescopes, a variety of Mac astronomy apps, two specialized digital cameras, and yet another camera, a Canon Eos 50D DSLR.</p><p>Speaking with Illig at length, it’s hard not to question the definition of “amateur” in the astrophotography game. The retired military analyst tells the story of a friend, “who bought a complete observatory from Vanderbilt University for about $250,000” and is now looking for a place in Maryland to set it up. And we thought $2,500 for a MacBook Air was expensive!</p><p>Illig has become a Mac evangelist among his fellow amateur astronomers. Whether as a result of his efforts or simply because of the Mac’s growing popularity, being a Mac-centric astrophotographer isn’t as lonely as it used to be. More and more MacBook-toting attendees are showing up at astronomy conferences, and software developers are paying due respect too.</p><p> “One of the foremost developers of astronomy software for amateurs and professionals is Software Bisque,” Illig says. “For years they paid scant attention to the Mac, issuing one program in the pre-OS X days and then abandoning it. But now they’re doing a complete rewrite of all of their software, and it is all coming to the Mac. There are also several Mac-only developers, such as Microprojects, whose software I rely on extensively.”</p><p>Illig has so much experience with astrophotography, he could probably shoot astrophotos in his sleep—and has likely nodded off after many nocturnal hours spent cooped up in his vault-like observatory, which is equipped with very few creature comforts. But to a newbie, capturing a single shot of, say, the Horsehead Nebula, would seem—and really is—quite complicated. </p><p><img alt="image of Horsehead and Flame nebulas" height="260" src="/files/u36/ODD_1_380_0.jpg" width="380" /><br /><strong>Illig captured this image of the Horsehead and Flame nebulas in the constellation Orion especially for this article. “The bright star is Alnitak, and it is visible to the naked eye as the leftmost star in Orion’s belt,” Illig says.</strong></p><p><strong>How to Mac-ify a deep-space photo.</strong> For Illig, astrophotography starts with the right tech setup: Two MacBook Pros, two telescopes, an astronomical CCD camera, a computer-controlled telescope mount, and planetarium software. Illig keeps a detailed list, categorized by season, of his desired “targets,” and starts an astrophotography session several hours—or even several months—before the date and time that should allow optimal conditions to capture the image he wants. </p><p>When the heavens align to his liking, he launches a planetarium app such as Microprojects Equinox, Starry Night Pro, or Software Bisque TheSkyX—which displays detailed sky maps with accurate coordinates for objects he’s looking for, and sends this info to his Mac-controlled telescope mount. He uses another Microprojects app, Equinox Image, to control his cameras, as well as the telescope mount. </p><p><a href="/files/u36/ODD_2_1000_0.jpg" class="thickbox"><img alt="Illig inside his observatory" height="253" src="/files/u36/ODD_2_1000.jpg" width="380" /></a><br /><strong>Illig inside his cramped observatory. The gray box in the lower right is his main CCD imaging camera. The white machinery in the middle is his computerized telescope mount. Photo by: Leona Illig; Click image to enbiggen </strong></p><p>“To confirm that the telescope is pointing at the desired target, I make a short exposure with my astronomical CCD camera and inspect the image frame on the Mac display,” Illig says. “I also use this test exposure to frame and compose the image just as you would with any regular photo.” </p><p>Next, Illig fine-tunes the positioning of the telescope by hand, and at this point he’s not far away from capturing the shot, which, as you might guess, isn’t a matter of simply clicking a shutter button. Celestial objects are not only very dim, but also have a pesky habit of “moving” across the sky, thanks to the earth’s rotation. Because of their dimness, Illig’s exposure times can last up to 10 minutes, and to keep his images from blurring, his telescopes have to follow an object’s path very precisely. </p><p>This is where the second telescope and yet another camera come in. “That second telescope is mounted atop the imaging telescope in ‘piggyback’ fashion. It, too, has a CCD camera attached,” Illig says, “but it’s a guide camera rather than an imaging camera.”</p><p>With his guide camera now communicating directly to his imaging camera via USB, Illig shoots a photo of a star close to his target object, centers that star in the guide camera’s frame, then clicks on it onscreen to identify it in Equinox Image. He now instructs the software to run a calibration routine, during which it moves the telescope in small amounts on the X and Y axes and photographs the guide star, measuring its position relative to the telescope. In essence, the calibration tells the software how to control the movement of the guide camera, while the main camera is simultaneously capturing the target object. </p><p>“The telescope mount is now slaved to the Mac software,” Illig says, “so if the guide star begins to move from its original position—a certain pixel on the CCD sensor—the software will move the telescope to compensate, and the star will remain centered.”</p><p>So is it time he snap the shot? Nope. We’re not there yet.</p><p><strong><br />Focus, focus, focus. </strong> Illig now has to focus the image, which (once again) isn’t as straightforward as it sounds. “I set the camera-control part of the software to Focus mode, in which it takes a series of exposures and downloads them to the Mac for my examination.”</p><p>With the camera-control software, Illig moves the camera inward toward the telescope a very small amount, until the image is a little less sharp than it was to start with. Then he does the opposite, moving the camera away from the telescope, until the image is sharply focused. “This is necessary because of the gravitational pull on the camera,” Illig explains. “Achieving focus while moving the camera upward, against gravity, results in better focus than moving it downward to the correct focus zone.”</p><p>OK—finally. Illig is now ready to take a picture! Or, as he puts it, not really a picture but “the first of a number of exposures that will be required to achieve one presentable monochrome or color image.” </p><p>Because his imaging camera has no built-in filters, Illig uses filters inserted into a filter wheel that’s also controlled by his Mac. His filter palette includes Red, Green, Blue, Luminance (clear), and Hydrogen Alpha, which corrects a particular wavelength of red light emitted when hydrogen gas in certain nebulas undergoes a change in energy level.</p><p><a href="/files/u36/ODD_4_1000_0.jpg" class="thickbox"><img alt="image of Comet SWAN" height="285" src="/files/u36/ODD_4_1000.jpg" width="380" /></a><br /><strong>A photo of the Comet SWAN that Illig shot in 2006. “The comet’s tail was very faint and required enhancement in Photoshop,” Illig says. “The result has a somewhat unnatural look.” Click image to enbiggen<br /></strong></p><p>To produce a color image, Illig takes a number of photos through each of the three color filters, R, G, and B. For each exposure through each color filter, Illig double-checks the focus and camera position vis-à-vis the location of the guide star, then instructs the camera to take an exposure of varying length, depending on the brightness of the sky. </p><p>At the end of the exposure time, the camera uploads the photo to Illig’s Mac. He checks it out and makes any necessary adjustments, then sets the camera-control software to tell the camera to take a series of photos in a row. “As the first exposure is beginning, I black out the MacBook Pro display so that no stray photons are reflected on the telescope,” Illig says. “From that point until exposures are complete, there’s nothing for me to do in the observatory except sit in the dark.”</p><p>But Illig doesn’t do that. Instead, he goes back into the house, where he uses another Mac to monitor the MacBook Pro in the observatory via screen sharing. He can also view the images as they come in, pull them onto his other Mac via his wireless network, and start to process them.</p><p>Processing is a multistep process (but of course!). Illig enlists software like Nebulosity from Stark Labs, which, in a nutshell, allows the astrophotographer to “stack“ a number of exposures of the same target to produce a single image. Once satisfied with his color image, Illig saves it as a TIF, opens it in Photoshop, and applies PictureCode’s Noise Ninja filter. </p><p><img alt="image of Moon" height="263" src="/files/u36/ODD_5_380.jpg" width="380" /><br /><strong>For more of Illig’s deep-sky pictures, see<a href="http://www.primordial-light.com/" target="_blank"> www.primordial-light.com </a></strong></p><p>The very last step is to show the image to his wife, Leona, a writer and photographer herself. With a thumbs up from Leona, he closes the book on that particular photo by posting it on his website. And, yes, friends, that really is where it all ends. For despite all the time, money, research, and fine-tuned finagling that Illig puts into his craft, he really is just an amateur astrophotographer. This isn’t a moneymaking enterprise, and he says he hasn’t scored any “coups” to wow the astronomy community.</p><p> “No, no coups,” Illig says. “My aim is to make pretty pictures.” </p>http://www.maclife.com/article/feature/using_macs_take_pictures_galaxies_far_far_away#commentsAstrophotographerFeaturesTue, 27 Jan 2009 17:11:32 +0000Leslie Ayers3775 at http://www.maclife.com